Process of producing nitro compounds.



. To all whom it may concern:

UNITED, STATES PATENT OFFICE.

OSKAR BOETERS AND RICHARD WOLFF NSTEIMOF BERLIN, GERMANY.

rnocnss or. PRODUCING m'rno comrotmns,

Specification of Letters Patent.

Patented June 1, 1909.

npplicationfiled July 30, 1907. Serial No. 386,259.

Be it known that we, 'Osm Bonrnas and RICHARD WOLFFENSTEIN, subjects of the German Emperor, and .residingat. Berlin, Gnrmany, have invented a certain new and 'useful Improved Process of Producing Nitro Compounds, of which the following is a specificationr The present invention has for its object an improved process of producing nitro compounds.

Nitro compounds which contain phenol groups are, generally speaking, produced by allowing nitric acid to ,act on the phenols; nitro-phenol or picric acid is thus formed from phenol, for example, in known manner.

This method of producing nitro-compounds presupposes that the hydroxyl group is already present in the compound which is to be nitrated; The introduction of a hydroxyl group into an organic compound'is, however,

as is known, an operation which can only be 1 carried out with more or less difliculty. Now We have found that this previous introduction of the phenol group is superfluous, and that the entry of the hydroxyl groupoand of the nitro group can be effected in one operation, which moreover is very simple, when the nitrating process by. nitric acid or azotic oxids is efl ected in the-presence of mercury or mercury compounds; thus nitro-phenol or picric acid is formed from benzol, for example. In this manner it is superfluous to produce the phenol at first previously from the benzol. This reaction has proved usable in all benzol compounds which have been examined. That the reaction does take place may be outwardly clearly known by the fact that the reaction mixture develops large quantities of nitrous gases duringthe entire period of the experiment which must, of

course, form in the reaction because the oxygen which is usedfor the formation of-the hydroxyl grou is taken out of 'the nitric acid, whereby t e formation of nitrous gases (azoticoxid etc.) is easily explained.

It may be mentioned that the introduction of hydroxyl groupsbesides the diazo group into the nucleus of aromatic compounds by nitrous acid in the presence of mercury ormercury compounds 1s known from the German patent specification 161,954; anthrachinone 1s, for example, converted into'l-oxyl.

diazo-anthrachinone. In order to illustrate the scope of the reaction in accordance with the present invenamounts to 38% in tion, some examples will now be given, in

connection with which it may be particularly emphasized that the nitration is completed 'moreor less according to the quantlty or concentration of the nitric acid which is employed in each case Example 1. For producing picric acid, 400- grm. ben'zol are heated with 660 grm. nitric acid (1,48) and 50 grm. mercuric nitrate or, another mercuric compound in the water-bath. The product of the reaction, which contains nitro-benzol at the same time, is then subjected to distillation in order to remove this; picric acid remains in the residue; yield :180 grmi The reaction is effected, in so far as the formation of picric acid is concerned, according to the equation cHa+ s o n mog on nno amo.

acid. Thesubstitut1on-products of benzol behave in this reaction like benzol; tri-nitro-' creosol and mono-nitro-oxy=benzoic acid are formed from toluene for example. The latter acid is also formed in nitrating benzoic acid in the presence of nitrate of mercury, which reaction proceeds well with a nitrlc acid of specific gravity 1,3 5. An abundant quantity of picric acid, as well as chlormtrophenol is formed from chlorid of benzol with 50% nitric acid, and nitro naphthalene as well as: 12% nitro-naphthols are formed from, naphthalene with nitric acid of likewise 50%. i i

As already mentioned the example iven above can easily result in difierent yiel s by varying the quantity and concentration of the nitric acid. Also, heterocyclic com-.

pounds with aromatic ring nuclei admitof the same reaction. For example, from quinolin a nitro-oxy-qumonn is formed which has the characteristic properties of nitro-" oXy-quinolin: solubility in soda, capability of being precipitated from this solution by acetic acid, a characteristic reddish coloration by chlorid of iron etc. The exact con-, stitution of this nitro oxy-quinolin has not yet beendetermined. As illustrating that, besides the nitro group, two hydroxyl groups have also been introduced by the above re action, anthra-quinone may be mentioned which forms a characteristic deep blue dye in this reaction; this formation of coloringmatter is efiected in the an'thraaquinone series, as is known, only when at least 2 hydroxyl groups are present in the compound.

\Vhat we claim as our invention and desire to secure by Letters Patent is 1. A process of producing nitro .compounds, consisting in heating aromatic compounds which are to be nitrated with a mixture of nitric acid and a mercury salt, and

in distilling oil the volatile products from the nitro phenols which are produced.

2. A process of producing nitro compounds, consisting in heating aromatic compounds which are to be nitrated with a mixtu're of nitric acid and mercuric nitrate, and in distilling off the volatile products from the nitro phenols which are produced.

3. A process of producing picric acid consisting in heating a mixture of benzol nitric acid and mercuric nitrate, and in distilling off the volatile products from the residue of picric acid.

In testimony whereof, we aifix our signatures in the presence of two witnesses.

- OSKAR BOETERS.

RICHARD 'WOLFFENSTEIN.

\Vitnesses:

E. BoRNs'rmN ERICH PELTNER. 

